Generator for currents in the order of mega-amperes through the use of explosives



Nov. 11, 1969 KNOEPFEL ET AL 3,478,231

GENERATOR FOR CURRENTS IN THE 012mm OF MEGAAMPERES THROUGH THE usm 0F EXPLOSIVES Filed May 20. 1966 2 mvmrons Heinz Knoepfel Fritz Herloch BY m,fiw,m m

ORNEYS United States Patent 3,478,231 GENERATOR FOR CURRENTS IN THE ORDER OF MEGA-AMPERES THROUGH THE USE OF EXPLOSIVES Heinz Knoepfel, Frascati, Rome, and Fritz Herlach, Grottaferrata, Rome, Italy, assignors to European Atomic Energy Community-Euratom, Brussels, Belgium Filed May 20, 1966, Ser. No. 551,655 Claims priority, application Italy, May 22, 1965, 11,312/ 65 Int. Cl. H02k 45/00 U.S. Cl. 310 6 Claims ABSTRACT OF THE DISCLOSURE A device for generating intense electrical currents through explosive compression of magnetic flux, comprising a conductor shaped to form a compression chamber, load transmission lines, a wall separating the load from the compression chamber, whereby an explosion of said chamber reduces the inductance of the system.

The present invention concerns a device which utilizes explosives as a source of energy for the creation of magnetic fields and of high intensity currents. Various methods are known for the conversion of chemical energy of an explosion into electromagnetic energy. The basic principle of these methods resides in compression through explosion of an electric conductor enclosing a magnetic field initially generated by conventional electric methods. In this process, the current of the system as well as the magnetic field which is tied in with it are notably amplified. In general, all these methods are destructive in the sense that each system ceases to exist after the creation of said magnetic field.

A system is known which utilizes the implosion of a metallic cylinder in order to compress the flux initially enclosed therein, said implosion occurring as a result of a cylindrical explosive charge placed upon the external surface of said metallic cylinder.

Such a system presents, however, the disadvantage that the explosive charge is necessarily very complex in order to avoid irregularities in the compression process. In the process of use, furthermore, the entire system and, therefore, also the pertinent apparatus which is connected thereto is completely destroyed.

The present invention is based upon an electrical system in which a current I (generated by a bank of condensers) produces a flux according to the formula:

wherein L is the initial inductance of-the circuit. Said system is compressed by the action of a chemical explosive in such a manner as to diminish the inductance of said circuit. Supposing that in this transformation, the magnetic flux which is enclosed remains constant, a supposition which is rigorously valid only for perfect conductors, the reduction of the inductance in the system must be followed by an increase of the current since it follows that:

during the entire compression process. There is therefore an increased current according to the formula:

where 'y is called the compression co-efiicient and in practice may achieve values from 100 to 200.

3,478,231 Patented Nov. 11, 1969 'ice The total energy of the system increases by the same factor, in fact:

a) E L1 L0 This in practice, signifies that the work performed by the explosive is transformed into electromagnetic energy, that is' the electromagnetic energy which finally results is given or obtained from the product of the compression factor and the initial electromagnetic energy.

The device according to the invention is constituted by a conductor body disposed in a manner to form successive lyi a compression chamber (in contact with which there is placed the explosive), a transmission line and a load, said load being separated from said compression chamber by means of the transmission line extending through a protective wall which is between said load and saidchamber, said compression chamber assuring the closing of the electrical circuit during the occurrence of the explosion in such a manner as to permit the reduction of the inductance in said circuit.

According to one embodiment of realization, the conductor body is constituted by two flat parallel metallic conductor walls which converge at one end into one end of the transmission line nearest the load and are connected at the other end by a fiat metallic end conductor wall and by the source of initial current, appropriate means being provided for the initial closing of the circuit through said source, and wall and parallel walls.

According to another embodiment, the conductor body is constituted by two coaxial metallic cylinders electrically connected at one end through the source of initial current, the external cylinder converging at its other end towards the internal cylinder so as to form therewith the coaxial transmission line and toroidal load.

According to a still further embodiment, the explosive is placed in an internal cavity in the compression chamber.

Denoting by I the maximum current which can be generated in a given system and by L L and L the respective inductances of the compression circuit, of the transmission line and of the load there will be obtained:

( c+ e+ tI It follows that, in order that the compression co-efiicient be sufiiciently high, the following must apply:

In practice this condition is the same as saying that the proposed generator is useful if tied in with a small inductance load (L Upon the conductor part which forms the compres sion chamber, there is disposed the chemical explosive in a manner that, being detonated, firstly closes the circuit and thereafter compresses the conductor without electrically interrupting the circuit in order to obtain the desired reduction of the circuit inductance L.

With an appropriate selection of the type' and of the dimensions of the transmission line, it is possible to safeguard the load circuit and the various measuring apparatus connected thereto. The matter of safeguarding the load not only represents an optimum-desideratum from the economic point of view but also permits a utilization of magnetic fields and of the generated currents also after mam.-

. having reached the maximum compression, which thereby 3 embodiments referred to the annexed drawings in which:

In FIGURE 1 is presented an embodiment of the device according to the invention, wherein the conductor is constituted by a fiat lamina of copper shaped in a manner so as to form in continuous manner the system circuit;

In FIGURE 2 is illustrated a variation of the invention wherein the conductor body is constituted by a series of coaxial cylinders;

In FIGURE 3 there is illustrated another embodiment of the invention wherein the explosive is placed internally of the compression chamber.

The subject device, shown in FIGURE 1 in lateral view, is constituted by a cavity 1, wherein occurs the implosion, delimited by two parallel metallic walls 2, for example, in flat copper having a thickness of 1 mm. which act as conductors for the initial current as well as containers and compressors of the magnetic flux; at one end said walls converge at 3 into one end of transmission line 4 which is remote from load 5 and continue parallel and nearer to each other along the transmission line which extends between the compression chamber 1 and the load 5. The two metallic walls 2 are an integral part of the electrical circuit, schematically represented in the figure, into which there is discharged the condenser bank 9, by means of the switch 8. An end or bottom 7, also metallic, connects, by means of the condenser bank 9 and the switch 8, the metallic Walls 2. In proximity to the bottom 7 of the compression chamber 1 there is placed a metallic lamina 10 appropriately shaped so as to assure the closing of the electrical circuit at the initial instant of implosion.

The explosive 6, of the plastic type, is placed externally along the walls 2 and 3 and possess a variable thickness between 0.4 and 1.6 cm. The detonation is primed simultaneously, for example by two detonators 14 in such a manner as to have the initial current I at the maximum when, following the detonation, the system closes upon itself by means of the shaped lamina conductor 10. The dash lines 11 and 12 represent the walls 2 deformed by the shock wave in two successive instances of the implosion. The protective wall 13, properly disposed out of contact with and spaced from the explosive, provides safeguarding of the load 5 and the various measuring apparatus connected thereto from the effects of the implosion. The detonators 14 are located at the end of the compression chamber which is remote from load 5 in order to effect primarily a closing of the circuit and thereafter a progressive compressing of the flux chamber without interrupting the electrical circuit. This applies to all embodiments.

In FIGURE '2 is represented in section a variation of the invention in which the device is constituted by an assembly of coaxial cylinders 15 and 16 extending along the transmission line 4, cylindrically symmetrical and terminating at the load 5 which is of toroidal shape.

The explosive 6 externally surrounds the cylindrical surface 15 as well as the truncated conical surface 17 and is primed by detonators 14 located at the base of cylinder 15. A circular ring bottom 10' assures the closing of electrical circuit at the initial instant of implosion.

In FIGURE 3 there is represented in section another variation of the invention wherein the explosive 6 is placed in a cavity 18 internally of the compression chamber. The dash lines 11 and 12 in FIGURE 3 represent two successive deformations of wall 18 at successive stages of the explosion initiated by detonator 14. Wall 18, thereby maintains a closed electrical circuit during the occurrence of the explosion. Walls 2 in FIGURE 3 remain substantially unaffected by the explosion.

The herein disclosed embodiments and the details thereof are for illustrative and not limitative purposes, the scope of the invention extending to all obvious modiflcations and embodiments which fall within the scope of the invention as claimed.

What is claimed is:

1. A device for generating electric currents in the order of mega-amperes, said device being of the type wherein a magnetic fiux is compressed through the action of explosives and comprising: an electrical circuit including a conductor body, a source of initial current connected to said body, and a transmission line connected directly to said body for transmitting current from said body to a load, said conductor body defining a flux compression chamber within which magnetic flux is induced by current flow through said circuit, an explosive arranged relative to said conductor body whereby detonation of said explosive deforms said body in a direction whereby there occurs a compression of the magnetic flux within said chamber, a protective wall spaced from and out of contact with said explosive isolating said body on one side of said wall, said transmission line passing through said wall, said conductor body comprising two parallel spaced apart conductor wall converging at one end thereof into one end of said transmission line, said body and said explosive being so arranged that upon detonation of said explosive there occurs a compression of said flux from an end of said body progressively towards said converging walls.

2. A device for generating electric currents in the order of mega-amperes, said device being of the type wherein a magnetic flux is compressed through the action of explosive and comprising: an electrical circuit includ ing a conductor body, a source of initial current connected to said body, and a transmission line connected directly to said body for transmitting current from said body to a load, said conductor body defining a flux com pression chamber within which magnetic flux is induced by current flow through said circuit, an explosive arranged relative to said conductor body whereby detonation of said explosive deforms said body in a direction whereby there occurs a compression of the magnetic flux within said chamber, a protective wall spaced from and out of contact with said explosive isolating said body on one side of said wall, said transmission line passing through said wall, wherein said conductor body comprises two parallel spaced apart conductor walls converging at one end thereof into one end of said transmission line, a flat conductor wall at the other end of said parallel walls and extending therebetween and being electrically in series with said parallel walls and said source of initial current, switch means for selectively closing the circuit from said source to said body.

3. A device for generating electric currents in the order of mega-amperes, said device being of the type wherein a magnetic flux is compressed through the action of explosives and comprising: an electrical circuit including a conductor body, a source of initial current connected to said body, and a transmission line connected directly to said body for transmitting current from said body to a load, said conductor body defining a flux compression chamber within which magnetic flux is induced by current flow through said circuit, an explosive arranged relative to said conductor body whereby detonation of said explosive deforms said body in a direction whereby there occurs a compression of the magnetic flux within said chamber, a protective wall spaced from and out of contact with said explosive isolating said body on one side of said wall, said transmission line passing through said wall, wherein said conductor body comprises two concentrically spaced apart conductor cylinders electrically connected together at one end thereof by means of said source of initial current, at the other end the external one of said cylinders converging towards the internal one and thereafter continuing parallel therewith as a coaxial transmission line extending through said protective wall, said coaxial line forming a toroidal shaped load on the ohter side of said wall.

4. The device of claim 1, wherein said explosive is arranged on the external surface of said conductor body in conformity with the outline of said surface, said conductor body having opposed ends respectively nearest to and remotest from said protective wall, detonators for said explosive located on said body at the end remote from said wall said body being progressively collapsible beginning at said end remote from said protective wall towards the end nearest said protective wall.

5. The device of claim 1, wherein said explosive is arranged internally of said body whereby it is surrounded by said flux chamber, said explosive being contained in an inner wall portion of said body which is surrounded by an outer wall portion thereof, said flux compression chamber being defined between said inner and outer wall portions, said outer wall portion being substantially undeformable while said inner wall portion is adapted to deform outwardly towards said outer Wall portion and progressively from one end of said body towards said converging Walls.

6. The device of claim 1, wherein said conductory body parallel walls and said conductor body converging walls together with said transmission line constitute an integral body of uniform material.

References Cited UNITED STATES PATENTS 2,224,337 12/1965 Ford et a1. 89-8 3,113,272 12/1963 Cannon et al 328-1 3,225,227 12/1965 Biehl 310-11 3,254,564 6/1966 Morley et al 89-8 3,295,412 1/1967 Morley et al. 89-8 3,356,869 12/1969 Hilton et al 310-10 MILTON O. HIRSHFIELD, Primary Examiner D. F. DUGGAN, Assistant Examiner US. Cl. X.R. 89-8; 307-106 

